Impregnation of wood, &amp;c.



reases.

IMPREGNATIUN 01F WOOD, dw.

specification of Letters Patent.

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Patented nee. a. rare.

lilo Drawing. .dpplteatton filed December'd, 1913, Serial No. 80t,608. Renewed December 7, 1917. Serial no. aoaaaa ject of the Emperor all) . certain new and To all whom, it may canoe .r I

Be it known that 1, Max Rtirrnc, a subdf Germany, residing Germany, have invented. useful Improvements in lmpregnation of Wood, &c., of which the following is a specification.

My invention relates in general to methods for preserving wood and similar materials, and more particularly to impregnating the materials with preservative liquids.

My present invention has for its object to improve the method of preserving wood, and other materials, v Letters Patent No. 12,707, dated October 22nd, 1907. in the practice of themethod covered by the said reissued Letters Patent, the timber, or other material to be treated, is subjected to an air or gas pressure previous to its immersion in the preserving liquid, the pressure being maintained and increased so that the pores, cells, and cavities in the material are first filled with air or gas of high pressure, which, after the material has been thoroughly penetrated by the impregnating liquid, and the pressure has been at Berlin, Prussia,

released, expands and forces out of the material a portion of the preserving liquid.

In the practice of the method coveredby my said patent, prior to my present invention, air has been exclusively used as the gas under pressure to which the material has been subjected in order that the excess preservative liquid may be expelled from the material under treatment. The use of steam as the gas under pressure has heretofore not been considered feasible, inasmuch as the pressure of steam depends upon its temperature, and in most cases the material to be treated, for instance wood, must not be subjected to a higher temperature than 240 151, and hence the available pressure of steam for this purpose is approximately 15 lbs, which is inadequate to satisfactorily secure the desired results.

. By my present invention the use of steam in. t

covered by U. S. Reissueduid through the cells and fibers of the wood,

not only facilitates the permeation of the wood by the liquid, but also expedites the ejection of the excess liquid by the expansion of the air inclosed in the individual pores and cells of the wood when the pressure around the same is released. In my improved method the Wood, or other material, is subjected to steam and air in succession before it is treated with the impregnating liquid, con: sequently the material is first heated and moistened by the steam at low pressure and is then subjected to air at higher pressure than that of the steam.

in the practice of my improved method the wood or other material is inclosed within a retort and subjected tolow pressure steam, preferably notexceeding 1-5 lbs. to the square inch. Preferably before admitting the steam to the retort, a vacuum is created therein which renders it possible to use steam at lower pressure and promotes the rapid penetration of the steam into the material.

While the material is still subjected to the action of thesteam, compressed air of higher pressure than the steam is admitted into the.

retort and allowed to penetrate the material. The compressed air entering the cells and pores of the material is moistened and heated by the steam and water of condensation which is formed in the retort and in the material assoon as air under pressure is ad- .mitted into the retort. The air distributes the wood, ior other material un-' c and the timber so cooled and dried as to ,pressure,'and which has accumulated at the bottom of the retort is drawn off and the retort is then filled with the preservative liquid so as to entirely submerge the material therein. More of the preservative liquid is then forced into the retort, thereby in creasing the pressure .above that of the steam and air so as to force the preservative liquid into the material. I

After the material has absorbed a suflicient quantity of the preservative liquid, the pressure is released to that of the atmosphere and theliquid is withdrawn from the retort. The compressed air confined in the cells and pores of the material then expands with great force and expels the surplus preservative liquid from the pores of the material. The material is then preferably subjected to vacuum in order to evaporate thewater of condensation which has accumulated'in the cells and pores of the material during treatment. The vacuum has the further eflect of removing additional quantities of the preservative liquid from the material.

While in the preferred practice of my improved method the timber, or other material under treatment, should not be subjected to a vacuum after being steamed, as the steam would therebybe expelled from the timber impair the desired effect of the steam, yet if the timber under treatment has not been thoroughly seasoned it may prove advisable to subject the timber to a vacuum after being steamed and prior to the subjection thereof to compressed air.

From the foregoing description it will be observed that I have invented an improved method of impregnating wood or similar material with a preservative liquid, by the practice of which a better and more thorough distribution of the creosote oil, or other preservative liquid, is secured; the rapidity of saturation is promoted; the necessary quantity of the preservative liquid is minimized; and the material under treatment is sterilized. These several advantages are primarily attained through-the subjection of the material to steam at comparatively low pressure prior to exposing the material to .air or gas under a greater pressure.

1. The method of preserving wood and similar materials, which consists in subjecting the material to steam, then subjecting the material to air or gas under pressure higher than that of the steam while the material is still subjected to. the action of the steam, and then while maintaining the pres sure around the material subjecting the same to an impregnating. liquid under pressure.

2. The method of preserving wood and similar materials, which consists in subjecting the material to steam, then subjecting the material to air or gas under pressure higher than. that of the steam while the material is still subjected to the action of the steam, then while maintaining the pressure around the material subjecting the same to an impregnating liquid under pressure, and finally relieving the pressure around the material and subjecting the same to a vacuum.

3. The method of reserving wood and similar materials, whic consists first in subjecting the material to pressure below that of the atmosphere, then subjecting the material to steam, then subjecting the material to air or gas under pressure higher than that of the steam while the material is still subjected to the action of the steam, and

then while maintaining the pressure around r of the atmosphere, then subjecting the material to steam, then subjecting the material to air or gas under pressure higher than that of the steam while the material is still subjected to the action of the steam, then while maintaining the pressure around the material subjecting the same to an impregnating liquid under pressure, and finally relieving the pressure around the material and subjecting the same to a vacuum.

5. The method of preserving wood and similar materials, which consists in subjecting the material to steam at less than fifteen pounds pressure, then subjecting the material to air or gas under greater pressure than the pressure of the steam while the material is still subjected to the action of the steam, and then while maintaining the pressure around the material subjecting the same to an impregnating liquid under still greater pressure.

6. The method of preserving wood and similar materials, which consists in subjecting the material to steam at less than fifteen pounds pressure, then subjecting the mate rial to air or gas under greater pressure than the ressure of the steam while the material is still subjected to the action of the steam, then While maintaining the pressure around the material subjecting the same to an impregnating liquid under still greater pressure, and finall relievin the ressure around the material and sub ecting t e same to a vacuum.

7. The method of preserving wood and similar materials, which consists in first subjecting the material to pressure below that of the atmosphere, then subjecting the material to steam at less than fifteen pounds pressure, then subjecting the material to air or gas under greater pressure than that of the steam White the material is still suhjeet- I mail suhjeetmg the same to an impregnatingliquid under still greater pressure, and any telieving the pressure around the ma,- teriel and suhjecting the same to e vacuum,

'itnesses: I

HENRY Heseee, Wem HA. 

